Triplet molecular oxygen

Solution Running a Sfable calculation indicates that the computed UHF wavefunction for triplet molecular oxygen is stable ... 

A. Peroxidation with Triplet Molecular Oxygen and Peroxy-radical... 

In some cases, the structures of oxygenation products have been crucial for assigning the structures of unusual radical cations. Eor example, the endo-peroxides (83 and 85) support the structures assigned to radical cations (24 and 84 ) derived from l,l-diaryl-2-methylenecyclopropane (23) and 2,5-diaryl-l,5-hexadiene, respectively.Time-resolved spectroscopic data suggest that 83 is generated by coupling of triplet biradical (24 ) with (triplet) molecular oxygen. 

The role of spin in the reaction is an especially interesting and important issue in carbene chemistry. Apparent violation of the spin selection rule, such as the reaction of ground state singlet carbene with triplet molecular oxygen in matrices as well as in solution, and the reaction of triplet ground-state carbenes with (singlet) CO, CO2, and N2 in matrices, are challenging issues for the near future. 

Seip M, Brauer H-D. Endoperoxide formation of helianthrene with triplet molecular oxygen. A spin-forbidden reaction. J Am Chem Soc 1992 114 4486-4490. 

Brady Clark K, Howard JA, Oyler A. Retinoic acid oxidation at high oxygen pressure evidence for spin-forbidden direct addition of triplet molecular oxygen. J Am Chem Soc 1997 119 9560-9561. 

The reaction of triplet molecular oxygen with radicals formed photochemically... 

Since triplet molecular oxygen behaves like a diradical, an interesting reaction has been observed between triplet oxygen and 5-methyl-2-phenyl-l,3-dithiolylium-4-olate (76). Treatment of (76) in acetonitrile with molecular oxygen at room temperature in the dark results in the formation of (80) in 45% yield. 

Furthermore, the radical cation (37 ), produced by electrolysis and/or by the use of one-electron-oxidizing agents, appears totally inert vs triplet molecular oxygen, envisaging, also in this case, an inefficient Barton-type reaction. The whole of these complex results, of course, induce an easy question what factors control whether radical cations, chemically and/or photochemically generated, react with oxygen species or not ... 

The special electronic configuration of triplet molecular oxygen (see Fig. 3-13) is responsible for the radical character and for the relative inertness of this extraor-... 

Fig. 6.2 Activation of triplet molecular oxygen ( 02) by electronic excitation or by consecutive one-electron reductions and the corresponding electron configurations of the resulting reactive oxygen species.

Figure 7.1 Cartoons of singlet and triplet molecular oxygen, (a) Triplet oxygen.

For the chemiluminescence reactivity, the imidazopyrazinone ii-system has a high HOMO level sufficient to react with triplet molecular oxygen. In the chemiluminescence experiment, an alcohol is employed as a solvent for stock solutions of imidazopyrazinone. The stock solution is mixed with an aprotic solvent such as DMSO containing base under O2, and this initiates the chemiluminescence reaction. A reason to use the alcohol solvent for stock solutions is explained by... 

Recent studies 19) have shown that reaction of triplet molecular oxygen with carbanions in the gas-phase proceeds only if the electron affinity of the corresponding organic radical is less than 20 kcal. In such cases, spin inversion apparently occurs by the device of an electron jumping from the carbanion to the oxygen molecule to generate the radical pair which subsequently collapses to the singlet peroxy anion (eq. 3). 

TURRO, N. J., M. F. Chow, and Y. Ito Autoxidation of Ketenes, Diradicaloid and Zwitterionic Mechanisms of Reactions of Triplet Molecular Oxygen and Ketenes. J. Amer. Chem. Soc. 100, 5580 (1978). 

A transition complex with triplet molecular oxygen may also be formed ... 

When the two oxygen atoms of O2 are incorporated into a product molecule, there must be a change in spin state. The reaction between triplet molecular oxygen and a singlet state... 

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